Aerodynamic rear drag reduction system for a trailer

ABSTRACT

A drag reduction system is configured to be coupled to a rear frame assembly of a trailer including a rear swing door and a rear frame. The drag reduction system includes a main wall panel configured to be coupled to a vertical member of the rear frame to extend generally rearwardly of the trailer at least partially along a height of the trailer. The main wall panel is pivotable relative to the rear frame between a deployed position wherein the inner surface of the wall panel is spaced-apart from the outer surface of the rear swing door, and a stowed position wherein the inner surface of the wall panel is adjacent to and engaged with the outer surface of the rear swing door.

This application is a Continuation of U.S. patent application Ser. No.14/049,506 filed Oct. 9, 2013 entitled AERODYNAMIC REAR DRAG REDUCTIONSYSTEM FOR A TRAILER, which claims priority under 35 U.S.C. §119(e) toU.S. Provisional Patent Application Ser. No. 61/720,163 filed Oct. 30,2012 entitled AERODYNAMIC REAR DRAG REDUCTION SYSTEM FOR A TRAILER, theentirety of each of which is hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to semi-trailers, such asvan-type trailers, for example. In particular, the present inventionrelates to an aerodynamic rear tail system for reducing drag on such atrailer.

BACKGROUND OF THE INVENTION

To reduce wind flow resistance and drag on a trailer, truck,semitrailer, or other vehicle, side skirts which extend downwardly froma bottom of the trailer and/or chassis toward the roadway to partiallyenclose the floor assembly and undercarriage of the trailer, fairingsand other such structures have been used. Many structures associatedwith the rear of the trailer are provided in order to also reduce theaerodynamic drag on the trailer.

A typical storage container of a trailer terminates with a large,rectangular rear surface. This shape causes an area of reduced pressureto be created behind the trailer storage container as it moves over thehighway, thus generating a slowing force that must be overcome withadditional engine power and thus additional fuel. In other words, airflow passing behind the vehicle imparts a drag force to the vehicle.Rear trailer fairings are designed to streamline the rear end of thetrailer in order to control the flow of air at the rear of the vehicle.Such reduction on the drag of the ground vehicle may operate to conservefossil fuels as well as other sources of vehicle drive power for hybridvehicles, battery-operated vehicles, and alternative fuel-basedvehicles, for example. However, many such fairings which cover the rearend of the trailer also may cover the rear doors of the trailer whichmust be opened and closed by a user to load and unload the cargo withinthe storage area of the trailer in such a way that users may be requiredto dismount and mount the fairing(s) each time a loading or unloadingoperation is to be performed.

SUMMARY

The present invention may comprise one or more of the features recitedin the attached claims, and/or one or more of the following features andcombinations thereof.

According to one aspect of the present disclosure, a drag reductionsystem configured to be coupled to a rear frame assembly of a trailerincluding a rear frame and a rear swing door includes a main wall panelconfigured to be coupled to a vertical member of the rear frame toextend generally rearwardly of the trailer at least partially along aheight of the trailer. The main wall panel is pivotable relative to therear frame assembly between a deployed position wherein the innersurface of the wall panel is spaced-apart from the outer surface of therear swing door, and a stowed position wherein the inner surface of thewall panel is adjacent to and engaged with the outer surface of the rearswing door.

In one illustrative embodiment, the main wall panel may be configured toextend below a bottom edge of a rear sill of the rear frame of thetrailer.

In another illustrative embodiment, the main wall panel may define alength greater than a height of the sidewall of the storage container ofthe trailer.

In still another illustrative embodiment, a top edge of the main wallpanel may be positioned at a non-perpendicular angle relative to innerand outer edges of the main wall panel.

In yet another illustrative embodiment, the drag reduction system mayfurther include a secondary wall panel configured to be pivotablycoupled to the rear swing door of the trailer. Illustratively, thesecondary wall panel may be configured to be coupled to a top portion ofthe rear swing door. Further illustratively, the secondary wall panelmay include a first portion configured to be coupled to a top portion ofthe rear swing door and a second portion pivotably coupled to the firstportion for movement about an axis parallel to a top edge of the rearswing door. The second portion of the secondary wall panel may beconfigured to engage a top edge of the main wall panel when the mainwall panel is in the deployed position. Further, an inner surface of thesecond portion of the secondary wall panel may be configured to engageand lie adjacent to an outer surface of the main wall panel when themain wall panel is in the stowed position.

In still another illustrative embodiment, an outer surface of the mainwall panel may be configured to engage the sidewall of the trailer whenthe main wall panel is in the stowed position.

In yet another illustrative embodiment, the main wall panel may beautomatically moved to the deployed position when a user moves the rearswing door to a fully-closed position. Further illustratively, the mainwall panel may be automatically moved to the stowed position when a usermoves the rear swing door to a fully-opened position.

In still another illustrative embodiment, the drag reduction system mayalso include an inner limit strap having a first end coupled to an innersurface of the main wall panel and a second end configured to be coupledto an outside surface of the rear swing door of the trailer. The innerlimit strap may operate to prevent outward movement of the main wallpanel relative to the swing door beyond a predetermined distance.Further illustratively, the drag reduction system may also include anouter limit strap having a first end coupled to an outer surface of themain wall panel and a second end configured to be coupled to the rearframe assembly of the trailer. The outer limit strap may operate toprevent inward movement of the main wall panel relative to the rearswing door beyond a predetermined distance.

According to another aspect of the present disclosure, a drag reductionsystem configured to be coupled to a rear frame assembly of a trailerincludes a main wall panel configured to be coupled to the rear frameassembly to extend generally rearwardly of the trailer at leastpartially along a height of the trailer. The drag reduction systemfurther includes a secondary wall panel configured to be coupled to therear frame assembly to extend generally rearwardly of the trailer atleast partially along a width of the trailer. The secondary wall panelis positioned above and engaged with the main wall panel.

In one illustrative embodiment, a top edge of the main wall panel may beengaged with and supports a bottom surface of the secondary wall panel.

In another illustrative embodiment, the main wall panel may be pivotablerelative to the rear frame assembly about a vertical axis. Further, thesecondary wall panel may be pivotable relative to the rear frameassembly about a horizontal axis. Illustratively, the drag reductionsystem may also include an inner limit strap and an outer limit strap.Illustratively, the inner limit strap may include a first end coupled toan inner surface of the main wall panel and a second end configured tobe coupled to an outside surface of the rear frame assembly of thetrailer in order to prevent outward movement of the main wall panelrelative to the swing door beyond a predetermined distance. Furtherillustratively, the outer limit strap may include a first end coupled toan outer surface of the main wall panel and a second end configured tobe coupled to the rear frame assembly of the trailer in order to preventinward movement of the main wall panel relative to the rear frameassembly beyond a predetermined distance.

In still another illustrative embodiment, the main wall panel may beconfigured to extend below a bottom edge of a rear will of the rearframe of the trailer.

In yet another illustrative embodiment, the secondary wall panel mayinclude a first portion configured to be coupled to a top portion of therear frame assembly and a second portion pivotably coupled to the firstportion for movement about an axis parallel to a top edge of the rearswing door.

According to still another aspect of the present disclosure, a dragreduction system configured to be coupled to a rear frame assembly of atrailer including a rear frame and a rear swing door includes a mainwall panel configured to be coupled to the rear frame assembly to extendgenerally rearwardly of the trailer at least partially along a height ofthe trailer. The main wall panel is pivotable about a vertical axisrelative to the rear frame assembly. The drag reduction system furtherincludes a secondary wall panel including (i) a first portion configuredto be coupled to a top portion of the rear frame assembly to extend atleast partially along a width of the traile, and (ii) a second portionpivotably coupled to the first portion for movement about a horizontalaxis relative to the rear frame assembly. The secondary wall panel isengaged with and supported by a top edge of the main wall panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rear end portion of a trailer showinga drag reduction system of the present disclosure including a rearfairing structure coupled to a rear frame of the trailer and shown in afully-deployed position when the rear doors of the trailer arefully-closed.

FIG. 2 is a perspective view similar to FIG. 1 showing the doors of thetrailer partially opened such that the rear fairing structure is onlypartially deployed as it moves toward a fully-closed, or retracted,position.

FIG. 3 is a perspective view similar to FIGS. 1 and 2 showing the doorsin an opened position (with one door removed in order to better view therear fairing structure) and showing the rear fairing structure retractedand positioned adjacent an outer surface of the door.

FIG. 4 is a perspective view similar to FIGS. 1-3 showing the doors ofthe trailer in a fully-opened position adjacent the sidewalls of thetrailer and showing the rear fairing structure in the retracted positionbetween the doors and the sidewalls of the trailer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to illustrative embodiments shownin the attached drawings and specific language will be used to describethe same. While the concepts of this disclosure are described inrelation to a truck trailer, it will be understood that they are equallyapplicable to other vehicles generally, and more specifically toconventional flat-bed and/or box or van type trailers, examples of whichinclude, but should not be limited to, straight truck bodies, smallpersonal and/or commercial trailers and the like. Accordingly, thoseskilled in the art will appreciate that the present invention may beimplemented in a number of different applications and embodiments and isnot specifically limited in its application to the particularembodiments depicted herein.

Looking first to FIG. 1, a trailer 10 includes an aerodynamic rear dragreduction system 12 coupled to the rear frame assembly (including a rearframe 13 and rear doors 14 coupled to the rear frame 13) of the trailer10. Illustratively, the drag reduction system 12 operates to improve theaerodynamic efficiency of the trailer 10 by reducing drag and wind flowbehind the rear end of the trailer 10. In particular, the drag reductionsystem 12 operates to reduce airflow immediately behind the trailer 10as the trailer 10 is traveling down the road. As is discussed in greaterdetail below, the airflow immediately behind the rear end of the trailer10 is reduced because the drag reduction system 12 channels and controlsthe flow of air from the sides and top of the trailer 10 over the rearend of the trailer 10. This reduction of airflow behind the trailer 10may increase the fuel efficiency, or the efficiency of any other sourceof vehicle drive power, of the tractor/trailer combination.

Illustratively, the drag reduction system 12 extends behind the rearframe 13 and rear doors 14 of the trailer 10. As is further discussed inadditional detail below, the drag reduction system 12 is movable withthe rear doors 14 of the trailer 10 between a fully-deployed, or use,position, and a fully-closed, or storage position. As shown in FIGS. 1and 2, the trailer 10 includes a storage container 15 configured tocarry cargo therein. The storage container 15 includes sidewalls 11, afront end wall (not shown), the rear end frame assembly (including therear frame 13 and doors 14), a roof 22, and a floor assembly 24 whichall cooperate together to define an inside storage portion 25 of thecontainer 15 that is able to store various articles or goods therein.The trailer 10 further includes a rear wheel assembly, or bogie, 16, anda front support or landing gear (not shown) each coupled to the floorassembly 24 of the trailer 10. Illustratively, the floor assembly 24 ofthe trailer 10 includes various laterally-extending cross members (notshown) as well as longitudinally-extending floor boards 26. The frontend of the trailer 10 is configured to be coupled to a tractor (notshown) for towing the trailer 10 thereon, thus providing atractor-trailer assembly. It should be understood that while theaerodynamic drag reduction system 12 is shown for use with a trailer 10,the drag reduction system 12 may be coupled to any vehicle to reduce thedrag thereon.

Illustratively, the trailer 10 includes two drag reduction systems 12,as shown in FIG. 1. In particular, one system 12 is coupled to one rearswing door 14 of the trailer 10, while the other system 12 is coupled tothe other rear swing door 14 of the trailer 10. For the purposes of thedescription herein, however, only one drag reduction system 12 will bedescribed herein. However, it should be understood that the two dragreduction systems 12 of the trailer 10 are identical in configurationand function.

As shown in FIGS. 1 and 2, the drag reduction system 12 includes a mainwall panel 30 and a secondary wall panel 32. As shown in FIG. 1 anddiscussed in greater detail below, the main wall panel 30 is generallyvertically-oriented and is hingedly coupled to a vertical member 27 ofthe rear frame assembly 13 of the trailer 10. The auxiliary wall panel32 is adjacent the main wall panel 30 and is hingedly coupled to a topend of the swing door 14.

As shown in FIG. 1, the left main wall panel 30 of the first dragreduction system 12 is coupled to the left-most vertical member 27 ofthe rear frame 13 of the trailer 10 while the right main wall panel 30of the second drag reduction system 12 is coupled to the right-mostvertical member 27 of the rear frame 13 of the trailer 10.Illustratively, four hinges 29 are provided to pivotably couple the mainwall panel 30 to the rear frame 13. However, it should be understoodthat any suitable number of hinges may be used as well. Further, thehinge 29 may be any suitable hinge to allow for pivotable movement ofthe main and secondary wall panels 30, 32 such as, but not limited to, abutt hinge, a butterfly hinge, a living hinge, etc., in order to allowthe allow the main wall panel 30 and the auxiliary wall panel 32 tohingedly move relative to the rear frame assembly 13 of the trailer 30along a pivot axis 53 defined by the hinges.

As shown in FIG. 3, the main wall panel 30 includes a generallyrectangular body 34 defined by a top edge 36, a bottom edge 38, aninside edge 40, and an outside edge 42. Illustratively, the inside andoutside edges 40, 42 are parallel to each other and to the vertical post27 of the rear frame assembly 13. The bottom edge 38 generally extendshorizontally and is perpendicular to the inside and outside edges 40,42. As shown in FIG. 3, the outside edge 42 includes a notch 44 formedtherein. As is discussed in greater detail below, the notch 44 operatesto provide an opening for the door locking mechanisms and/or handles(not shown) of the rear door 14 to allow the panel 30 to be able to liegenerally flat against an outer surface of the rear door 14 when in theclosed, or retracted, position. The top edge 36, however, is notparallel to the bottom edge 38 and is not perpendicular to the insideand outside edges 40, 42. Rather, the top edge 36 is angled relative tothe other edges 38, 40, 42. Particularly, the top edge 36 is angleddownwardly from the outside edge 40 to the inside edge 42. It should beunderstood that while the top edge 36 is shown to be angled downwardly,it is within the scope of this disclosure for the top edge 36 to begenerally horizontal or angled upwardly as well. Further, it is withinthe scope of this disclosure to include a body 34 of the main wall panel30 defining inside and outside edges which are not parallel to eachother or to the vertical post 27 of the rear frame 13 to which the mainwall panel 30 is attached. As is discussed in greater detail below, thetop edge 36 of the panel 30 operates to support the secondary wall panel32 thereon when the drag reduction system 12 is in the use position, asshown, for example, in FIG. 1.

Illustratively, the body 34 of the main wall panel 30 extends below abottom edge 50 of the rear sill 52 of the rear frame 13 of the trailer10 such that the bottom edge 38 of the main wall panel 30 is positionedbelow the bottom edge 50 of the rear frame 13, as shown in FIGS. 1-4. Assuch, an overall length of the outside edge 40 of the main wall panel 30is longer than an overall length of the rear frame 13 of the trailer 10.Further, an overall length of the outside edge 40 of the main wall panel30 is greater than a height of the sidewall 11 of the storage container15 of the trailer 10. While the illustrative main wall panel 30 extendsbelow the rear frame 13, it should be understood that it is within thescope of this disclosure to include a main wall panel 30 having anysuitable length including one which does not extend below the rear frame13 of the trailer 10 and/or one which is generally equivalent in lengthto the rear frame 13 of the trailer 10.

As shown in FIGS. 1 and 2, the secondary wall panel 32 is coupled to atop portion of the rear swing door 14 and is configured to pivot aboutan axis 54 relative to the swing door 14. Illustratively, the secondarywall panel 32 includes a first portion 60 and a second portion 62hingedly coupled to the first portion 60. The first portion 60 iscoupled to the top portion of the swing door 14 and is configured toextend above a top edge 66 of the swing door 14. Illustratively, thefirst portion 60 extends generally upwardly to define a planar surfacegenerally parallel to the outer surface of the swing door 14. The secondportion 62 of the secondary wall panel 32 is coupled to the firstportion 60 via a hinged connection. As shown in FIGS. 1 and 2, and as isdiscussed in greater detail below, the second portion 62 is configuredto extend outwardly away from the first portion 60 and away from theswing door 14, as shown in FIG. 1 when the drag reduction system 12 isin the fully-deployed, or use, position. The second portion 62 is alsoconfigured to lie generally adjacent the first portion 60 such that theouter surface of the second portion 62 is generally parallel to thefirst portion 60, as shown for example in FIG. 3, when the dragreduction system 12 is in the stowed position.

Illustratively, the second portion 62 defines first and second outeredges 70, 72, a top edge 74, and a bottom edge 76. As shown in FIG. 2,the side edges 70, 72 converge toward each other from the top edge 74toward the bottom edge 76. Thus, a length of the bottom ledge 76 issmaller than a length of the top edge 74.

The drag reduction system 12 further includes an inner limit strap 80,shown in FIGS. 1 and 2. The inner limit strap 80 includes a first end 82coupled to an inner surface 83 of the main wall member 30 and a secondend 84 coupled to the outer surface 85 of the swing door 14. As isdescribed in greater detail below, the inner limit strap 80 operates tolimit the movement of the main wall panel 30 relative to the swing door14. In addition to the inner limit strap 80, the drag reduction system12 further includes an outer limit strap 90 having a first end 92coupled to an outer surface 93 of the main wall panel 30 and a secondend 94 coupled to the outer, vertical post 27 of the rear frame 13 ofthe trailer 10, as shown in FIGS. 1 and 2. As is discussed in greaterdetail below, the outer limit strap 90 also operates to limit movementof the main wall panel 30 relative to the swing door 14. In particular,the inner limit strap 80 operates to prevent outward swinging movementof the main wall panel 30 relative to the swing door 14 beyond apredetermined angle while the outer limit strap 90 operates to preventinward swinging movement of the main wall panel 30 relative to the swingdoor 14 beyond a predetermined angle. The length of the limit straps 80,90 may be made variable in order to selectively change the predeterminedangle beyond which the door 14 is unable to swing (both outwardly andinwardly).

In use, as noted above, the drag reduction system 12 operates toincrease aerodynamic efficiencies of the trailer 10 to which it isattached by smoothing the airflow behind the rear frame 13 of thetrailer 10 as the trailer 10 travels along a highway, for example.Illustratively, the drag reduction system 12 is movable between afully-deployed position, as shown in FIG. 1, and a retracted, or closed,position, as shown in FIGS. 3 and 4. In the fully-deployed position, thedrag reduction system 12 is operable to reduce the drag of the trailer10 as the trailer 10 travels along a highway, for example. As shown inFIG. 1, the main wall panel 30 extends outwardly away from the rearframe 13 of the trailer 10. Illustratively, the plane defined by themain wall panel 30 is neither parallel to nor perpendicular to a planedefined by the sidewall 11 of the trailer 10. The main wall panel 30 issimilarly neither parallel to nor perpendicular to a plane defined bythe rear frame 13. In other words, the main wall panel 30 is angledrelative to the sidewall 11 of the trailer 10 and is angled relative tothe rear frame 13 of the trailer 10. While the main wall panel 30 of thedrag reduction system 12 is illustratively shown to be angled relativeto the rear frame 13 by a particular degree, it should be understood,that it is within the scope of this disclosure to angle the main wallpanel 30 relative to the rear frame 13 by any suitable degree.

In the fully deployed position, the inner limit strap 80 and the outerlimit strap 90 cooperate to maintain the main wall panel 30 in thedeployed position. As noted above, the inner limit strap 80 operates toprevent the main wall panel 30 from pivoting outwardly about the axis 53relative to the rear frame 13 beyond a certain predetermined positionwhile the outer limit strap 90 operates to prevent the main wall panel30 from pivoting inwardly about the axis 53 relative to the rear frame13 beyond a certain predetermined position. Illustratively, the innerand outer limit straps 80, 90 may be made from any suitable, flexible orbendable, but generally non-elastic material. Further, while only oneinner strap 80 and one outer strap 90 are shown, it is within the scopeof this disclosure to include any number of inner and/or outer strapsfor maintaining the deployed position of the main wall panel 30.Further, it is within the scope of this disclosure for the dragreduction system 12 to include devices other than the inner and outerstraps 80, 90 for maintaining the deployed position of the main wallpanel 30. In other words, other stops or limiters may be coupled to themain wall panel 30 in order to prevent outward movement of the main wallpanel 30 relative to the swing door 14 of the trailer 10 beyond acertain predetermined position and to prevent inward movement of themain wall panel 30 relative to the rear frame 13 and the rear swing door14 beyond a certain predetermined position.

Looking still to FIG. 1, the secondary panel 32 of the drag reductionsystem 12 extends outwardly from the rear swing door 14 of the trailer10 when the system 12 is in the deployed position. Illustratively, aninner surface of the secondary panel 32 rests upon the top edge 36 ofthe main wall panel 30 when in the deployed position. As noted above,the top edge 36 of the main wall panel 30 is angled downwardly. As such,the secondary panel 32 is angled slightly downwardly as well. In otherwords, a plane defined by the second portion 62 of the secondary panel32 is not parallel to a top surface of the roof assembly 22 of thetrailer 10. Rather, the second portion 62 is angled downwardly.

When the drag reduction system 12 is in the deployed position, the swingdoors 14 of the trailer 10 are closed. The main and secondary wallpanels 30, 32 of each of the two drag reduction systems 12 extendoutwardly from the rear frame 13 and rear swing doors 14 in order todirect and smooth air flow around the rear end of the trailer 10 as thetrailer 10 travels down the highway, for example. The inner and outerlimit straps 80, 90 maintain the position of the main wall panels 30 ofeach drag reduction system 12 while the second portion 62 of thesecondary panel 32 rests upon the top edge 36 of the main wall panel 30of each respective system 12.

When the trailer 10 is not traveling on the road and it is necessary fora user or operator to open the rear doors 14 of the trailer 10 in orderto gain access to the storage area 25 of the storage container 15, theuser need only open the doors 14 in the usual or typical manner and thedrag reduction system 12 coupled to each door 14 automatically moves toits closed position, as shown in FIGS. 2-4. Looking to FIG. 2, as theswing door 14 is opened, the swing door 14 is moved toward the main wallpanel 30 while the main wall panel 30 remains generally stationaryrelative to the trailer 10. As the swing door 14 is moved closer to themain wall panel 30, the bottom surface of the second portion 62 of thesecondary panel 32 remains engaged with the top surface 36 of the mainwall panel 30. Once the outer surface 85 of the swing door 14 engagesthe inner surface of the main wall panel 30, the top edge 36 of the mainwall panel 30 no longer supports the second portion 62 of the secondarypanel 32. Thus, the second portion 62 of the secondary panel 32 pivotsdownwardly about the axis 54 such that the bottom surface of the secondportion 62 of the secondary panel 32 is engaged with the outer surfaceof the main wall panel 30. During movement of the swing door 14 towardthe main wall panel 30, the inner limit strap 80 collapses such thatthere is not tension on the inner limit strap 80, as shown in FIG. 2.Looking to FIG. 4, once the door 14 is moved to the fully-openedposition, the drag reduction system 12 is in the closed or retractedposition and is located between the outside surface of the swing door 14and the sidewall 11 of the trailer 10. The outside surface of the mainwall panel 30 and the outside surface of the second portion 62 of thesecondary panel 32 are each engaged with the sidewall 11 of the trailer10. The inner surface of the main wall panel 30 is engaged with theouter surface 85 of the swing door 14.

In order to move the drag reduction systems 12 to the opened, ordeployed, position, the user or operator need only move the doors 14 ofthe trailer 10 from their fully-opened position back to theirfully-closed position, shown in FIG. 1. In use, therefore, as the doors14 are closed, the drag reduction system 12 associated with each door 14is automatically moved to the deployed position. In particular, as theswing door 14 is moved from the fully-opened position shown in FIG. 4toward the closed position shown in FIG. 1, the drag reduction system 12associated therewith moves with the door 14. As noted above, thesecondary wall panel 32 is coupled to the door 14 for movementtherewith. Further, when the drag reduction system 12 is in thefully-closed position (and the door 14 is in an opened position), thesecondary wall panel 32 is positioned over the main wall panel 30 suchthat the secondary wall panel 32 moves with the door 14 as the door 14is moved from the opened position to the closed position. As such, themain wall panel 30 is also urged to move with the door 14 because thesecondary panel 32 covers the main panel 30 and carries it therewith.

As the door 14 is further moved toward the closed position and once themain wall panel 30 reaches the predetermined deployed position, theouter limit strap 90 prevents further movement of the main wall panel 30with the door 14. As the door 14 is further moved toward the closedposition, the main wall panel 30 remains generally stationary and thesecond portion 62 of the secondary wall panel 32 begins to pivotupwardly about the pivot axis 54. The second portion 62 is urged topivot upwardly because as the secondary wall panel 32 continues to movewith the door 14 as the door 14 moves to the closed position, the bottomsurface of the second portion 62 of the secondary wall panel 32 remainssupported by the top edge 36 of the main wall panel 30 and moves alongthis top edge 36 of the main wall panel 30 while the main wall panel 30remains relatively stationary. As such, the second portion 62 of thesecondary wall panel 32 is moved upwardly to the deployed position shownin FIG. 1.

In other words, it is not necessary to perform an extra step to move thedrag reduction system 12 to the closed position prior to opening thetrailer doors 14 or to move the drag reduction system 12 to the openedposition after closing the door 14. Rather, the drag reduction system 12automatically moves to the closed position upon opening the door 14 towhich the drag reduction system 12 is attached and moving the door 14 tothe fully opened position along the sidewall 11 of the trailer 10, asshown in FIG. 4. It should be understood that the drag reduction systems12 of the present disclosure may be used alone or in conjunction withother drag reduction systems such as, for example, aerodynamic sideskirts such as those disclosed in U.S. Pat. No. 8,177,286 and U.S.Patent Application Publication No. 2013/0249241, for example, theentirety of each of which is incorporated herein by reference.

Illustratively, each wall panel 30, 32 is made of a composite material.For example, the composite material may include a plastic core and metalouter skins coupled to the plastic core. Such a composite materialprovides a rigid, but lightweight and durable material. Illustratively,for example, each wall panel 30, 32 may be made of a DURAPLATE®composite panel provided by Wabash National Corporation of Lafayette,Ind. DURAPLATE® composite panels are constructed of a high-densitypolyethylene plastic core bonded between two high-strength steel skins.

The inner and outer skins respectively may be formed of a metal ormetallic composition, examples of which include, but should not belimited to aluminum, galvanized steel, full hardened steel, such as AISIGrade E steel, or the like. In one illustrative embodiment, for example,the outer skin is formed of ASTM G90 galvanized steel, and the innerskin is formed o ASTM G40 galvanized steel. In alternative embodiments,the inner and/or outer skins respective may be formed of other rigid,semi-rigid, metallic or non-metallic materials. Illustratively, thecomposite material (i.e., panels 30, 32) is approximately between 0.08inch and 0.20 inch thick, with a preferred thickness of approximately0.10 inch thick. While the illustrative panels 30, 32 disclosed hereinare each made of the particular composite material described above, itshould be understood that other suitable composite materials may be usedas well. For example, the panels 30, 32 may also be made from a plasticpultrusion with fiber reinforcements embedded inside the polymermaterial. The reinforcement fibers may be made from glass, carbon,and/or other suitable materials, for example.

It should be further understood that while the illustrative panels 30,32 disclosed herein are made from a composite, the panels 30, 32 mayalternatively be formed from a non composite material such as a sheetmade from a metal, metal alloy, or plastic, for example. The panels 30,32 may be made from ferrous or nonferrous materials including plasticsor composites incorporating a combination of ferrous and/or nonferrousmaterials thereof. In particular, an alternative panel (not shown) maybe made from galvanized steel. Of course, it is within the scope of thisdisclosure to include non-galvanized steel sheets, or other suchnon-composite panels, of any suitable thickness as well.

While the invention has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of theinvention are desired to be protected.

What is claimed is:
 1. A drag reduction system configured to be coupledto a rear frame assembly of a trailer including a rear frame and a rearswing door, the drag reduction system comprising: a main wall panelconfigured to be pivotably coupled to the rear frame assembly to extendat least partially along a height of the trailer; and a secondary wallpanel configured to be pivotably coupled to the rear swing door of thetrailer adjacent a top edge of the rear swing door of the trailer toextend at least partially along a width of the trailer, wherein the dragreduction system is pivotable relative to the rear frame assemblybetween a deployed position wherein the main wall panel and thesecondary wall panel each extend generally rearwardly of the trailer,and a stowed position wherein an inner surface of the main wall panel isadjacent to and engaged with the outer surface of the rear swing doorand a bottom surface of the secondary wall panel is adjacent to andengaged with an outer surface of the main wall panel, and

wherein the secondary wall panel is configured to engage a top edge ofthe main wall panel when the drag reduction system is in the deployedposition, and
 2. The drag reduction system of claim 1, wherein a topedge of the main wall panel is positioned at a non-perpendicular anglerelative to a pair of forward and rear edges of the main wall panel. 3.The drag reduction system of claim 2, wherein the top edge of the mainwall panel angles downwardly when the main wall panel is in the deployedposition.
 4. The drag reduction system of claim 1, wherein a pivot axisof the secondary wall panel is spaced rearwardly apart from the rearframe assembly.
 5. The drag reduction system of claim 1, wherein thesecondary wall panel is angled downwardly when the rear drag reductionsystem is in the deployed position.
 6. The drag reduction system ofclaim 1, wherein secondary wall panel extends farther rearwardly thanthe main wall panel when the rear drag reduction system is in thedeployed position.
 7. The drag reduction system of claim 1, wherein thetop edge of the main wall panel is positioned inwardly of an outer edgeof the secondary wall panel when the rear drag reduction system is inthe deployed position.
 8. A drag reduction system configured to becoupled to a rear frame assembly of a trailer, including a rear frameand a rear swing door, the drag reduction system comprising: a main wallpanel configured to be coupled to the rear frame assembly to extendgenerally rearwardly of the trailer at least partially along a height ofthe trailer; and a secondary wall panel configured to be coupled to therear frame assembly to extend generally rearwardly of the trailer atleast partially along a width of the trailer, wherein the secondary wallpanel is positioned above and engaged with the main wall panel, whereina top edge of the main wall panel is engaged with and supports a bottomsurface of the secondary wall panel and the top edge of the main wallpanel is positioned inwardly of an outer edge of the secondary wallpanel, and wherein the secondary wall panel is angled downwardly andextends farther rearwardly than the main wall panel.
 9. The dragreduction system of claim 8, wherein the wherein the main wall panel ispivotable relative to the rear frame assembly between a deployedposition wherein an inner surface of the wall panel is spaced-apart fromthe outer surface of the rear swing door, and a stowed position whereinthe inner surface of the main wall panel is adjacent to and engaged withthe outer surface of the rear swing door, and wherein the secondary wallpanel is pivotable relative to the rear swing door between a deployedposition wherein a bottom surface of the secondary wall panel isspaced-apart from the outer surface of the rear swing door, and a stowedposition wherein the bottom surface of the secondary wall panel isadjacent to and engaged with the outer surface of the main wall panel.10. The drag reduction system of claim 9, wherein a pivot axis of thesecondary wall panel is spaced rearwardly apart from the rear frameassembly.
 11. The drag reduction system of claim 9, wherein movement ofthe main wall panel from its deployed position to its stowed positionautomatically causes the secondary wall panel to move from its deployedposition to its stowed position adjacent the outer surface of the mainwall panel.
 12. The drag reduction system of claim 8, wherein the mainwall panel is angled inwardly such that a rear edge of the main wallpanel is positioned inwardly of a forward edge of the main wall panel.13. The drag reduction system of claim 8, wherein an outer edge of thesecondary wall panel is not parallel to an inner edge of the secondarywall panel.
 14. The drag reduction system of claim 8, wherein a top edgeof the main wall panel is not parallel to a bottom edge of the main wallpanel.
 15. The drag reduction system of claim 14, wherein the top edgeof the main wall panel angles downwardly.
 16. A drag reduction systemconfigured to be coupled to a rear frame assembly of a trailer includinga rear frame and a rear swing door, the drag reduction systemcomprising: a main wall panel configured to be coupled to the rear frameassembly to extend generally rearwardly of the trailer at leastpartially along a height of the trailer, wherein the main wall panel ispivotable about a vertical axis relative to the rear frame assembly; anda secondary wall panel configured to be coupled to a top portion of therear swing door to extend at least partially along a width of thetrailer for pivoting movement relative to the rear frame assembly,wherein the secondary wall panel is engaged with and supported by a topedge of the main wall panel, wherein the drag reduction system ispivotable relative to the rear frame assembly between a deployedposition wherein the main wall panel and the secondary wall panel eachextend generally rearwardly of the trailer, and a stowed positionwherein the main wall panel and the secondary wall panel are generallyplanar with the rear frame assembly, and wherein a pivot axis of thesecondary wall panel is spaced rearwardly apart from the rear frameassembly.
 17. The drag reduction system of claim 16, wherein a top edgeof the main wall panel is engaged with and supports a bottom surface ofthe secondary wall panel, and the top edge of the main wall panel ispositioned inwardly of an outer edge of the secondary wall panel whenthe drag reduction system is in the deployed position.
 18. The dragreduction system of claim 16, wherein the secondary wall panel is angleddownwardly and extends farther rearwardly than the main wall panel whenthe drag reduction system is in the deployed position.
 19. The dragreduction system of claim 18, wherein a top edge of the main wall panelangles downwardly.
 20. The drag reduction system of claim 16, wherein aninner surface of the main wall panel is adjacent to and engaged with theouter surface of the rear swing door and a bottom surface of thesecondary wall panel is adjacent to and engaged with an outer surface ofthe main wall panel when the drag reduction system is in the stowedposition.